Determine what songs will be included in your routine. The songs should not only be upbeat and fast-paced -- around 136 to 144 beats per minute -- but also catchy and memorable. Consider songs that are relatively unknown, as opposed to songs being played ad nauseam on the radio; in other words, avoid what everyone else is playing.
Mix your cheers with loop-based music software (see "Resources"). Mixing your cheerleading routine yourself generally takes lots of time and energy to learn; you may also consider a professional cheerleading music mixing company.
Insert sound effects into your mix. These sound effects should be used sparingly and be perfectly timed with your choreography. A large number of weird sound effects will put people off, but one or two sound effects timed with choreography will make your routine sparkle.
Make sure the music flows naturally from song to song and is not abrupt. Make sure song transitions match up with your eight-count choreography. Look at party mixes, either online or in stores, for professional examples and ideas.
Avoid including cheers in your routine, if possible, although high school cheers may require them. If you must do a cheer, make sure it is high-energy and fits well with the rest of your routine. Try to put a beat behind your routine that fits in with the rest of your song.